Her parents died when she was 7, and her uncle and aunt, Mordecai and Esther Hayes of Newlin Township, Pennsylvania, adopted her and raised her.
Under General Philip Kearny, she established the first Union army hospital south of the Potomac River, at a seminary near Manassas, Virginia, and led a medical team of 40 men.
General Ulysses S. Grant gave her free passage on all railroads and steamboats operating against the Confederate capital and ordered his officers to assist her.
Painter managed hospitals, cared for wounded men, wrote letters for them, and distributed medical and commissary supplies.
[1][2][4] In 1868, Painter moved to the western territories, visiting her sons, who worked for the Union Pacific Railroad in Cheyenne, Wyoming, and Corinne, Utah, respectively.